Answer:
10in
Step-by-step explanation:
8-3=5
5+5=10
The 9 is a coefficient because it is the first one before an 'algebraic number'. :)
5x+2y=7
y=x-7
5x=7-2y
5x=7-2(x-7)
5x=7-2x+14
5x+2x=7+14
7x/7=21/7
<u>x=3
</u>y=x-7
<u />y=3-7
<u>y=-4
</u>
Answer is B<u>
</u>
Without any calculations it's evident it can't be neither B (both numbers are even, so they're divisible by 2) nor C (the numbers end in 0 and 5, so they're divisible by 5).
A.

Both numbers have a factor of 3, so they're not relatively prime.
That means it must be D. But, let's check it.

Indeed, those two numbers are relatively prime.